from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker, scoped_session, declarative_base

from app.config.config import config
from app.settings import env
def db_connect():
    # 创建一个引擎 ,目的：连接到本地的mysql数据库
    config_class=config[env]()
    engine=create_engine(config_class.db_url,echo=config_class.if_echo,pool_size=10,max_overflow=30)
    #打开数据库连接对话
    session=sessionmaker(engine)
    #保证线程安全
    db_session=scoped_session(session)
    #获取基类
    Base=declarative_base()

    return Base,db_session,engine
